1. Field of the Invention
The present invention relates to an armrest for use in such a vehicle seat as an automotive seat, and in particular is directed to the one of the vertically rotatable type wherein the armrest is free to rotate between a non-use position where it stands upright along the lateral side of seat back of the seat and a use position where it lies horizontally for receipt of an occupant's arm.
2. Description of Prior Art
Conventionally, by and large, most of the vertically rotatable armrest utilizes a spring means for urging the armrest body to one of use and non-use positions and resiliently holding it there, the use position being defined hereby as a position in which the armrest lies horizontally, projecting forwardly relative to the seat back of a seat, and the non-use position being defined hereby as a position in which the armrest is in the state of being stood generally upright along the vertical lateral side of the seat back.
The displacement of such spring-based armrest between the use and non-use position is effected in relation to a dead point, which is hereby defined to be a point disposed at a center line between the use and non-use position, where the force of the spring is not active or turned to zero as it appears and does not act on the armrest to rotate to wards either of the non-use and use positions. In other words, when rotating the armrest downwardly below the dead point towards the use position, the armrest is urged to rotate donwwardly by virtue of the pulling force of the spring and its own weight without adding any further force thereupon, or when rotating the armrest upwardly above the dead point towards the non-use position, the armrest is to be rotated with a force overcoming the force of the spring until the dead point and beyound the dead point, the armrest is automatically forced into the non-use position under the pulling force of the spring without applying any further force to the armrest.
Thus, the above spring-based armrest displays what can be called a "semi-automatic" operation for displacement between the use and non-use positions when the armrest passes by such dead point.
However, it has been perceived as a drawback in this kind of armrest that, the armrest body, when being rotated down below the dead point, is so quickly forced down as to cause a serious collision between the relevant part and a stopper within the body. In particular, in the case of such armrest being mounted on the front seat, with a console box being disposed along the lateral side of the front seat, the armrest will be driven into a strong crush with the console box, emitting an unpleasant noize. As a result, such aspect has been disadvantageous for use by an occupant.